Updates golang/go#18273

Change-Id: I2e7589d070a2953972bc8456d572edd616525266
Reviewed-on: https://go-review.googlesource.com/34271
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tom Bergan <tombergan@google.com>